Porsche Cayman Top Speed: The Porsche Cayman GT4 3.8 981 - [2015] has a top speed of 183 mph (294.5 kph) Porsche Cayman Acceleration: This Cayman accelerates 0-60mph (96.6 kph) in 4.2 seconds or 0-100kph in 4.3 and can achieve an estimated 1/4 mile drag time in 12.67 seconds with a trap speed of 107.9 mph.